Add needs job output (#629)

* Add outputs field to job model

* Add output interpolation for jobs

* Add otto config reference for interpolated job output values into 'needs' context

* Add output interpolation call after job has completed.

* gofmt

* Remove whitespace

* goimports

Co-authored-by: Casey Lee <cplee@nektos.com>

pkg/runner/step_context.go

@@ -29,6 +29,7 @@ type StepContext struct {
 	Env        map[string]string
 	Cmd        []string
 	Action     *model.Action
+	Needs      *model.Job
 }
 
 func (sc *StepContext) execJobContainer() common.Executor {
@@ -37,6 +38,19 @@ func (sc *StepContext) execJobContainer() common.Executor {
 	}
 }
 
+func (sc *StepContext) interpolateOutputs() common.Executor {
+	return func(ctx context.Context) error {
+		ee := sc.NewExpressionEvaluator()
+		for k, v := range sc.RunContext.Run.Job().Outputs {
+			interpolated := ee.Interpolate(v)
+			if v != interpolated {
+				sc.RunContext.Run.Job().Outputs[k] = interpolated
+			}
+		}
+		return nil
+	}
+}
+
 type formatError string
 
 func (e formatError) Error() string {